Method of manufacturing a glow-discharge tube

ABSTRACT

A character-indicating, glow-discharge tube is provided with a plurality of cathodes shaped in the form of characters. The individual cathodes are each supported by electrical leads which pass through openings in the bottom of the tube. Small insulating tubes, preferably made of glass, are disposed over the leads and extend from the cathodes into the openings in the bottom of the glow-discharge tube. A gastight seal between the leads and the glass tubes and between the glass tubes and the bottom of the glow-discharge tube is obtained by melting the ends of the glass tubes adjacent the openings in the bottom of the glow-discharge tube. Alternatively, the gastight seal is obtained with appropriate ceramic or glass-type solders depending on the material of the insulating tubes.

United States Patent Schiekel et al. 1 1 Aug. 5, 1975 [54] METHOD OF MANUFACTURING A 2,735,038 2/1956 Hancock 313/1095 x GLOWDISCHARGE TUBE 2,769,939 11/1956 Williams... 313/1095 x 3.042.833 7/1962 Willls 313/210 X 1 Inventors: nfr Schiekel; inz g, 3,437,861 4/1969 Koshizuka et at 313/1095 both of Ulm, Danube, Germany 3,519,865 7/1970 Weston 313/219 X [73] Assigneez Licefia patent verwanungs 3,570,000 3/1971 Koshlzuka et a1. 313/1095 X Frankfurt am Primary Examiner-Roy Lake Assistant E.taminerJ. W. Davie [22] Filed: May 29, 1973 Attorney, Agent, or Firm--Spencer & Kaye [21] Appl. No.. 364,681 [57] ST CT Related Application Data A character-indicating, glow-discharge tube is pro- [62] Divisio" of 389401 May 181 [970' vided with a plurality of cathodes shaped in the form abandoned of characters. The individual cathodes are each supported by electrical leads which pass through openings [52] 29/2516; 174/506]; 319/219 in the bottom of the tube. Small insulating tubes. pref- Cl. 1 t 1 1 erabiy a of g ara disposed over the ead d [58] Fleld Search 29/2513 '16; extend from the cathodes into the openings in the bot 313/210 317; /36 tom of the glow-discharge tube. A gastight seal be- 59; 74/5056 5059 tween the leads and the glass tubes and between the glass tubes and the bottom of the glow-discharge tube [56] Reta-"mes cued is obtained by melting the ends of the glass tubes adja- UNITED STATES PATENTS cent the openings in the bottom of the glow-discharge 2,014,809 9/1935 Kiihle et a]. 174/5059 X tube. Alternatively, the gastight seal is obtained with 2,071,597 2/1937 Vasselli 174/5061 appropriate ceramic or glass-type solders depending Kaufieldt 1 X on the material of [he insulating tubes 2,338,336 1/1944 Koch 1 1 1 174/5061 2,618,760 11/1952 Hancock et al 313/1095 5 Claims, 3 Drawing F igul'es PATENTED AUG 1975 SHEET OOOOOO Inventors. Manfred Schiekel Heinz Herzog cow e .1 :(L

ATTORN S.

PATENTEDAUE 5197s 3.891615 FIG. 2b

FIG] Inventors.

Manfred Schiekel Heinz Herzog ,awwt/ I" BY /ZJ ATTORNE S.

PATENTEUAUB 51975 3.897, 615 SHEET 3 lnventars. Manfred Schiekel Heinz Herzog BY Wei/21 f ATTORNEYS.

METHOD OF MANUFACTURING A GLOW-DISCHARGE TUBE CROSS REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 38,040, filed May 18, 1970 now abandoned.

BACKGROUND OF THE INVENTION The present invention generally relates to characterindicating, glow-discharge tubes and more particularly to a character-indicating tube having cathodes shaped in the form of characters and connected with electrical leads which are brought through the tube bottom in a gastight manner, the leads extending substantially linearly in the interior of the tube and being surrounded with insulating material.

Character-indicator tubes are known in which the individual cathodes are stacked and fastended to bars and the individual cathodes are connected with the leads in the tube bottom by separate connecting wires. Character-indicator tubes are also known in which the individual electrodes are fastened to appropriately guided leads and are supported thereby.

In all the known types of character-indicator tubes operating according to the glow principle, there exists the difficulty of preventing the glowing of the cathode leads. It is known to prevent the glowing of the leads by disposing the cathodes within a cup-shaped shielding electrode. Such a construction, however, is relatively expensive. It is further known to cover the leads to the individual cathodes with insulating material, for example with a ceramic paste. It has been shown in continu ous operation that such a covering does not dependably prevent glowing of the leads in the long run.

SUMMARY OF THE INVENTION It is the object of the present invention to provide a novel construction for a glow-discharge tube as well as a process for making the same which is simple to accomplish and in which glowing of the cathode leads is substantially eliminated.

According to the present invention, this is accomplished by providing an insulating material in the form of small tubes whose one end extends closely to the cathode and whose other end extends into openings in the tube bottom. The small tubes are in gastight connection with the edges of the openings in the tube bottom as well as with the leads passing therethrough.

The significant advantage of the glow-discharge tube according to the present invention lies in its extremely simple construction and in the simple manufacturing process therefor which is particularly suited to be incorporated into an automatic fabrication process. The insulating tubes employed by the present invention which are placed on the cathode leads prevent glowing of these leads and at the same time serve to produce the gastight seal of the leads in the tube bottom. A further advantage of the present invention is that it is possible to use a tube bottom made of metal to which there can be applied a defined potential to thereby render it insensitive to material precipitated by the cathodes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating the fastening of the cathodes in the tube bottom of a character-indicator tube according to the invention.

FIG. 2a is a plan view of the tube bottom of one embodiment according to the present invention.

FIG. 2b is a plan view similar to FIG. 2:: but of another embodiment.

FIG. 3 is a schematic view as seen from the top of the electrode structure of such a character-indicator tube.

FIG. 4 is a cross-sectional view taken along the longitudinal axis of a character-indicator tube constructed according to the invention.

FIG. 5 is a cross-sectional view taken perpendicular to the longitudinal axis of a character-indicator tube constructed according to the invention.

FIG. 6 is a bottom view illustrating one form of mounting the glow-discharge tube.

FIG. 7 is a side view further illustrating the form of mounting the glow-discharge tube shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in which like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIG. 3, a series of cathodes l which represents, for example, the numbers 0 to 9 are disposed one next to the other and insulated from one another within an anode 4 preferably of two parts and surrounding the cathodes. One of the anode portions 4 is in the shape of a grid whereas the other is, for example, of a suitable inperforate metal part. The tube is then read through the grid-shaped anode part.

As shown in FIG. 1, the individual cathodes, which in a character-indicator tube may have the shape of the individual FIGS. 0 to 9 are provided with appropriate leads 2. These leads 2 are substantially linear and may be of the same material as the figures being cut, for example, out of a piece of metal together therewith, or these leads may be of separate tapes, wires or the like which are connected with the individual figures by welding, for example. According to the invention, small tubes 5 of insulating material are pushed over the individual leads 2. These small tubes 5 should enclose the leads as tightly as possible and are pushed over the leads to such an extent that they come to lie as close as possible to the individual cathodes 1 thereby stiffening the leads 2. To assure proper spacing between the individual cathodes during manufacturing, it is advisable to use a plurality of gauges 3 sandwiched between the individual electrodes The gauges 3 are removed once the individual leads for the cathodes have been secured in the tube bottom 6.

The tube bottom 6 in the illustrated preferred embodiment according to FIGS. 1 and 2a is constructed of a metal piece having a number of openings 7 which correspond to the desired number of leads. These openings 7 serve for the passage of the leads and are so dimensioned that the tubes 5 of insulating material when placed over the leads can be inserted into these openings 7.

In a preferred embodiment of the present invention the tubes 5 are made of glass. To produce a gastight connection between these tubes 5 and the tube bottom 6 as well as between the leads 2 and the tubes 5, the tube bottom 6 is heated, after insertion of the tubes into these openings 7, for example by means of infrared radiators 8. The necessary heat may also advantageously be provided by means of high-frequency electromagnetic fields or by the coaction of different heating methods. The illustrated radiation heating is preferably directed toward the underside of the tube bottom 6 so that the bottom serves as a shield for the electrodes to protect them from the heat radiation. With increasing heating of the lead passage points. the ends of the small tubes 5 in the openings 7 begin to melt. This produces a gastight connection between these tubes 5 and the edges of openings 7 on the one hand and between the leads 2 and the ends of the tubes 5 on the other hand in the plane of the tube bottom 6. The ends of tubes 5 away from the cathodes thus form a type of head seal. With smaller tubes having a large number of leads. it may be advisable to provide a common opening for a plurality of leads in the tube bottom 6, e.g. in the shape of a slit 70 as shown in FIG. 2b, so that the stiffening tubes come to lie close together and, when they are glass tubes, sinter or melt together into a single glass block in the area of the passage points.

Although a preferred gastight seal is produced by melting the tubes, it is also possible to produce a gastight connection between the tubes and the tube bottom and the leads 2 with the aid of appropriate ceramic or glass type solders. if required, the tubes 5 may be made of a ceramic material and the gastight connections produced with the aid of the conventional metal solders.

FIG. 4 shows a longitudinal section through a charac ter-indicator tube constructed according to the present invention, and FIG. 5 shows a cross section of this tube in a plan view. The leads 2 which bear the individual cathodes l, are provided with small glass tubes 5 which are placed over the leads and extend up to the cathodes. The tube envelope includes a bottom 6 and a sheath 10, and the bottom is a metal piece provided with a flange 11 at its periphery sealed with the tube sheath l0. Sheath I is made of glass, and the seal with flange 11 is made by melting the base of the sheath. Alternatively, bottom 6 may also be made of glass. A number of openings are further disposed in the tube bottom 6, the diameter of these openings being selected so that the glass tubes just fit through. Cathodes 1, together with leads 2 over which the glass tubes 5 were pushed, are inserted into these openings in the tube bottom 6 so that the glass tubes at least extend into these openings or extend therethrough a certain amount. The spacings between the individual cathodes are determined by a guage in which all the figureshaped cathodes and, if required. also the anodes are fastened. By heating the passage point of the glass tubes 5 through the tube bottom 6, the glass tubes 5 are seealed with the tube bottom and with the leads 2.

The cross section shown in FIG. 5 shows that in the illustrated preferred embodiment of the present inven' tion the individual anode portions 4 are sealed into the tube bottom 6 with the aid of glass tubes 5 in the same manner as the figure-shaped cathodes I. Since a character-indicating tube constructed in this manner is read from the side, and only from one side, the rearward portion of the tube wall may be covered with a blackening layer 9.

The tube according to the present invention shown in FIGS. 6 and 7 permits a particularly suitable manner of mounting. In this tube. the leads 2 are arranged in two substantially parallel rows and the projections of the outwardly extending ends of the leads 2 are made to progressively increase in length in each row. Mounting and electrical contact with the tube 24 can be accomplished, due to the configuration of the leads 2 according to the present invention, by means of an insulating material piece 21 provided with conductive paths and connecting pins 22. The conductive paths 23 are preferably applied in the manner of a printed circuit and are disposed on the front as well as on the back of wafer 21 of insulating material. The thickness of the wafer of insulating material is preferably so selected that it can bc placed resiliently between the two rows of leads 2. The length of the conductive paths in the area of the connecting leads 2 is graduated in such a manner that each conductive path ends at its corresponding connecting lead as shown in FIG. 7. Thus, it is very easy to mount the gas discharge tube according to the present invention.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

We claim:

1. in a method for manufacturing a characterindicating, glow-discharge tube having a plurality of character-shaped cathodes each being provided with an electrical lead which supports the respective cathode at a distance from the bottom of the glowdischarge tube envelope, the improvement comprising the steps of:

a. tightly closing said leads by pushing small tubes of glass over each of said leads so that one of the ends of said tubes extends to each of said cathodes,

b. inserting the opposite ends of said small tubes into an opening in the bottom of the glow-discharge tube envelope and 0. connecting said small tubes to the leads and the edges of the opening in the bottom of the glowdischarge tube envelope to obtain a gastight seal by heating said small tubes to melt the portion of said small tubes in said opening so that said small tubes become fused with the leads and the edges of the opening, whereby said small tubes serve to provide both a gastight seal around the leads and to prevent glowing thereof.

2. A method as defined in claim 1 wherein the bottom of the glow-discharge tube envelope is made of glass and said step of connecting said small tubes further includes the step of melting the edges of the opening in the bottom of the glow-discharge tube envelope so that the small tubes and the corresponding edges are melted together.

3. A method as defined in claim 1 further comprising the step of arranging the leads with the corresponding small tubes in two parallel rows, which rows are spaced from each other so as to resiliently receive a mounting and electrical contact element.

4. A method as defined in claim 1 wherein there are a plurality of openings in the bottom of the glowdischarge tube envelope each associated with a respective lead and tube.

5. A method as defined in claim 1 wherein the glowdischarge tube has at least one anode with a corresponding lead connected to the anode. and further comprising the steps of: placing a tube of glass over the lead of the anode such that one end of the tube extends to the anode and the other end is inserted into an opening in the bottom of the envelope and connecting the tube associated with the anode to the respective lead and to the edges of the opening in the bottom of the envelope to obtain a gastight seal.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,897,615

DATED August 5th, 1975 INVENTOWS) Manfred Schiekel et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading of the patent after "[21] Appl. No. 364,681" insert [30] Foreign Application Priority Data May 17, 1969 Germany. .l925220-.

Column 2, line 48, after "electrodes" insert a period.

Signed and Scaled this twenty-fifth D ay 0f November 19 75 SE AL] A ttesr:

RUTH c. msou c. MARSHALL DANN Arresting Officer Commissioner ufPaIenls and Trademarks 

1. In a method for manufacturing a character-indicating, glowdischarge tube having a plurality of character-shaped cathodes each being provided with an electrical lead which supports the respective cathode at a distance from the bottom of the glowdischarge tube envelope, the improvement comprising the steps of: a. tightly closing said leads by pushing small tubes of glass over each of said leads so that one of the ends of said tubes extends to each of said cathodes, b. inserting the opposite ends of said small tubes into an opening in the bottom of the glow-discharge tube envelope and c. connecting said small tubes to the leads and the edges of the opening in the bottom of the glow-discharge tube envelope to obtain a gastight seal by heating said small tubes to melt the portion of said small tubes in said opening so that said small tubes become fused with the leads and the edges of the opening, whereby said small tubes serve to provide both a gastight seal around the leads and to prevent glowing thereof.
 2. A method as defined in claim 1 wherein the bottom of the glow-discharge tube envelope is made of glass and said step of connecting said small tubes further includes the step of melting the edges of the opening in the bottom of the glow-discharge tube envelope so that the small tubes and the corresponding edges are melted together.
 3. A method as defined in claim 1 further comprising the step of arranging the leads with the corresponding small tubes in two parallel rows, which rows are spaced from each other so as to resiliently receive a mounting and electrical contact element.
 4. A method as defined in claim 1 wherein there are a plurality of openings in the bottom of the glow-discharge tube envelope each associated with a respective lead and tube.
 5. A method as defined in claim 1 wherein the glow-discharge tube has at least one anode with a corresponding lead connected to the anode, and further comprising the steps of: placing a tube of glass over the lead of the anode such that one end of the tube extends to the anode and the other end is inserted into an opening in the bottom of the envelope and connecting the tube associated with the anode to the respective lead and to the edges of the opening in the bottom of the envelope to obtain a gastight seal. 